Tools for stripping covered wire



1969 2. BIEGANSKI 3,422,708

TOOLS FOR STRIPPING COVERED WIRE Filed Oct. 4, 1967 Sheet of 2 Iuvem-om;

ZDLISLHLJ BlGH/HSKI W Km 44% Jan. 21, 1969 2. SIEGANSKI TOOLS FOR STRIPPING COVERED WIRE Sheet Filed Oct. 4, 19

l veuTqe: zwus LAvJ T516 Gfimskl States 4 Claims ABSTRACT OF THE DISCLOSURE The invention provides a wire stripping tool in which the sheath of the wire is part severed and then displaced relative to the core of the wire, two pairs of jaws being provided, one for the part severing operation and the other for gripping the sheath, and the jaws being displaced relative to one another to strip the part severed portion. The two sets of jaws are linked by a toggle assembly having three links which are proportioned so that closing movement of one lever handle first closes the respective jaws and subsequently displaces the one set of jaws relative to the other, the transition between closing and displacement being determined by the nature of the wire being operated upon.

This invention relates to tools for stripping the sheath or covering of wire, especially electrical insulation ofi' single or multi-stranded conductive wires, the covering being of a material such that it can readily be severed by cutting and/ or tearing.

Tools of this kind comprising rst and second sets of pivoted jaws coupled to a lever mechanism, for example a pair of pivoted levers to make a pliers like tool, are well known in the art: one pair of jaws is closed to grip the sheath, and the second pair of jaws is closed to cut and part-sever the sheath. The cutting jaws may be located between the gripping jaws or vice-versa so that the movement of one pair of jaws is controlled by the other pair of jaws and this is followed by displacement of one set of jaws relative to the other to strip the partly severed covering off the core.

The problem in tools of this nature is to accommodate sheaths and wires and the like of varying materials and relative thicknesses in a single tool.

This problem is overcome, in accordance with the invention in that the displaceable jaws are both coupled to a common rod which is guided for axial movement and connected to said lever mechanism which includes at least one pivoted lever handle, whereby pivoting of the lever handle causes, at least in the final part of the pivoted movement displacement of the rod and said jaws.

Preferably, however, the jaws are coupled to a pivoted lever, forming part of the said lever mechanism, for jaw closing, and the displaceable jaws are also coupled to the said lever for displacement, the coupling including three links pivotally connected respectively to the lever, to a closable jaw, and to a displaceable jaw, the three links also being pivoted to one another so that different pairs of the three links form two sets of toggle linkages, the geometry being such that initial lever movement closes the jaws, without effecting displacement, and after the sheath is gripped and at least partly severed, continued lever movement effects displacement of the jaws without further closing.

Hence, the tool of the invention may be used with a range of thicknesses of sheath, and hence with a range of cable and like material sizes and types, by virtue of the transition between lever movement causing jaw closing and sheath penetration for severing and the lever movement causing jaw displacement for sheath stripping occuring at a point dependent upon the jaw closing moveatent O "ice ment being terminated by sheath resistance (possibly combined with spring resistance) and this results from the three link arrangement which arts as a double toggle linkage.

However, to enable a single tool to cope with an even greater range of cable sizes it may be desirable to provide adjustment means whereby the final closed position of one pair of jaws with respect to the other pair of jaws can be varied.

The invention will be further described with reference to the accompanying drawings which illustrate by way of example, four different manually operated tools according to the invention.

FIGURE 1 is a side view of the first embodiment in the open position;

FIGURE 2 is a side view of a fourth tool; and

FIGURE 3 is a detail thereof.

Referring now to the drawings and particularly FIG- URE l, gripping jaws 11 are formed at the ends of two outer lever arms 12 having longitudinal faces 13 sufficiently set back from the gripping surfaces to accommodate two inner lever arms 14 the ends of which carry notched sharp edge cutting jaws 15 here formed integrally by bending over the material of the arms 14.

Relative longitudinal movement between the jaws 11 and 15 is in this example produced by pivoting the ends of the inner arms 14 remote from the jaws by a pivot 16 to a pull-rod 17 coupled to a block 18 which is con nected on both sides to toggle linkage devices, the knee 19 of each toggle linkage device being pivoted to parts of the mechanism which are urged together by hand operation. The pu1l-r0d 17 carries an abutment 21 which engages one end of a preloaded compression spring 22 to resist the relative longitudinal movement.

Each of two hand levers 23 is pivoted individually at 24 to the sides of a frame 25 to which the lever arms 12 are pivoted at 26, the pull-rod 17 being guided through the pivot 26. A three link toggle is provided at each side of the mechanism, consisting of links A, B, C, these all being pivoted at knees 19; the link A being pivoted at its outer end at 27 to the hand lever 23, the link B being pivoted at its outer end at 28 to the jaw 12, and the link C being pivoted at its outer end to the block 18. Point 27 is remote from the pivotal connection 24 to the frame 25. The compression spring 22 abuts at its other end against an abutment 29 carried by an extension of the frame 25. A small compression spring 31 acts between the inner lever arms 14 to urge them, and through them, the arms 12 apart.

The frame 25 could comprise two plates between which the arms 12, 14 and hand lever ends are located.

The action of this tool in use, from the position shown in the drawing is as follows: The cable is inserted between the jaws 11 and its end portion extends between cutting edges 15. The two hand levers 23 are then closed together, and this action straightens each toggle linkage A, B, thus urging the links B substantially in straight lines to exert pressure on the jaws 11 and the inner lever arms 14 so as to close the jaws and the inner lever arms together on to the sheathed wire.

By suitably proportioning the links and the relative strength of the spring 22, a toggle arrangement is obtained whereby the block 18 at points 35 resists movement until such time that an incision is made in the sheath and the desired grip on the sheath is obtained by the jaws 11.

Consequently, all the force applied at this time is transferred, essentially due to the nature of the toggle linkages, for closing the gripping jaws on to the sheath, and the cutting jaws, because they are in advance of the gripping jaws, penetrate and part-sever the insulation sheath as referred to above.

During this movement pivot points 19 are displaced increasing in each case the angle between links B and C, thus placing links C in a more favourable position for subsequent action.

When the outer jaws 11 come into solid gripping contact with the sheath the resistance encountered limits and prevents further closure of the cutting edges 15 towards one another and hence stops the toggle action of links A, B.

At this point, pivots 19 lie in a favourable position with relation to pivot points 35, so that continued force applied to the handles 23 activate links C. This continued force, therefore, moves points away from the pivot 26 (overcoming the spring 22) so that the rod 17 displaces the cutting edges 15 away from the jaws 11, then drawing the severed portion of the sheath away from the portion still gripped between jaws 11. The rod 17 hence moves axially, that is, along the axis of the cable or parallel thereto.

Referring now to FIGURES 2 and 3, the tool shown therein is generally similar to that of FIGURE 1, but is simplified to comprise a single-sided tool; that is, it has a straight rigid member forming at one end portion a jaw provided with extension 111 which is serrated at 112, and also extends to form a first handle 113.

Substantially midway along its length the member is provided with a lateral extension 114 which locates a pair of pivotal blocks 115, 116. A second jaw 117 provided with an inwardly directed extension 118 having a serrated surface 119 is pivoted upon block for movement between the illustrated position and the position more closely adjacent the jaw 110 whereby a cable or the like shown in chain-dot lines at 120 inserted between the two serrated faces 112 and 119 may be gripped by these faces between the jaws.

A lever handle 124 is pivoted on the pivot block or spindle 116 for movement towards the handle portion 113 and for effecting closure of the jaws and other operations.

Located between the jaws 110 and 117 is a second pair of jaws 125, 126 pivoted on a spindle or the like 127 in a clevis block 128. Each of the jaws 125, 126 is provided integrally or as an attachment with an inwardly directed cutting surface 130 and the two surfaces may have V-shaped notches in their free edges, and one jaw is slightly longer than the other so that when the jaws 125, 126 are closed together one portion 130 slides over the other portion 130 and the V-notches or other means may cut into the cable sheath 120 to part sever the sheath.

Each of the jaws 125, 126 is guided for sliding movement relative to the length of the corresponding adjacent jaw 110 or 117 and for this purpose may have a boss 132 located in a shallow channel (not shown) on the inner face of the corresponding jaw 110, 117.

The jaws 125, 126 are spring urged apart by a small compression spring 135 received in blind bores in the adjacent faces of the jaws 125, 126.

The clevis block 128 is pinned at 139 fast with a rod 140 which extends through a transverse bore in the pivot block 115 and also through a co-axial bore in a projection 142 from the handle portion 113. This guides the rod 140 for axial sliding movement.

The jaws 117, the rod 140 and the handle 124 are connected by a three link toggle device comprising links 150, 151, 152 all of which are pivoted together at a common knee 153 and at their respective free ends are pivoted at 155 to the handle 124, at pivot 156 to the jaw 117 and at pivot 157 to the rod 140.

It is convenient to make projection 114 with parallel limbs so as to leave a space between them to house the jaw 117 for free pivotal movement upon the block 115 and similarly to fulcrum the handle 124. The jaw 117 may itself be slotted to accommodate link 151 and allow free pivoting of the latter about the Point 156, as y 4 the handle 124 so allow free pivoting of the link 150 about the pivot 155.

The inner jaw itself is spaced from the co-operating channel surface of the pivot jaw 117 by a variable amount by means of an adjustment screw 160 also shown in FIGURE 3. The screw has a milled head 161 (FIG- URE 3) and a neck 162 provided with a plurality, conveniently four, peripherally spaced shallow blind holes or recesses 163, and a spring loaded detent 165 is located in the free end of the jaw 117 as shown by the dotted line 165 and this detent is urged resiliently into engagement with any one of the recesses 163 according to the angular position of the screw.

The shank 166 of the screw is threaded and engages in co-operating threads in the jaw 117.

By turning the head 161 a different recess 163 is engaged with the detent 165 and because the angular movement advances the free end 167 of the screw into contact and displacement of the jaw 126, the relative positions of the cutting portion 130 and the gripping portion 119 respectively are varied.

It will be appreciated that initial closing movement of the lever 124 towards the handle portion 113 causes the link 152 to swing about its pivot 157 whilst the links 150, 151 act to displace the jaw 117 towards jaw 110. During this initial closing movement of the jaws link 151 travels substantially in a straight line.

The geometry of the three link arrangement is therefore one in which the link 152 travels beyond a line perpendicular to the length of link 151 during its initial closing movement.

Spring 170 is a compression spring of substantially greater value than spring 135, and spring 170 resists possible movement of pivot 157 during the initial closing movement so that at this stage, link 152 only pivots about point 157.

The closing movement continues until the cutting portions 130 penetrate the cable and essentially until the serrated surfaces 112, 119 grip the cable.

The resistance to deformation of the cable sheath limits and ultimately prevents further closing movement of the jaws and when the cable is properly gripped (this also depending upon the geometry of the linkage) the first part of the action is terminated (called the transistion point) and the continued handle 124 movement towards the portion 113 results in all three links moving relative to one another and in a toggle action whereby the end of link 152 adjacent to the spring 170 moves downwardly towards the extension 142 thus drawing the rod 140 axially and hence drawing the jaws 125, 126 away from the inwardly directed extensions 111, 118 of the jaws 110, 117.

This results in the end portion of the cable sheath being torn and stripped from the wire or other core of the cable.

The geometry of the linkage is further such that during the whole of the movement from the illustrated position of the handle 124 to a position where it is parallel with handle portion 113 when the jaws are closed upon the cable, links 150 and 151 do not travel beyond a straightline position, that is a position in which pivots 155, 153, 156 lie in a straight line. This in fact applies to all of the links, considered in pairs, that is links 150, 152 only move from the illustrated position to a more acute angle of one to the other and links 151, 152 move to a greater angle of one with respect to the other, without any pair of links going over-centre.

It will also be appreciated that in practice a single squeezing together of levers 113, 124 is a single action resulting in first gripping and then stripping of the cable with the transition between the two stages of the action taking place automatically.

The tool in practice may operate, with the screw 160 in any one position, upon a range of cable sheath overall diameters and cable core diameters without any adjustment being necessary.

However, the purpose of the screw 160 is to enable the tool to be used with an even wider range of cable diameters and core diameters.

The shank 166 of the screw has a fine thread so that the end is advanced a few thousandths of an inch only in each complete rotation, and any quarter revolution from one recess 163 to the next will displace the jaw 126 relative to the jaw 117 so as to take the tool from a position in which it will cope with a first range of sizes of cable and core to a position in which it will cope with a second range of sizes, the second range overlapping the first range. Hence in the majority of cases, an operator of the tool will be cable to use the tool at one setting of the screw for any of the different cable sizes with which the operator is working.

The face of the screw head which is visible in the assembled position shown in FIGURE 2 may be provided with indicia so as to enable the setting of the tool to be ascertained at a glance.

It will be appreciated that the single aided mechanism of FIGURES 2 and 3 in which one jaw and one handle portion are rigid with respect to one another is particularly useful for installing as part of a cable stripping machine for power action since the displacement of handle 124 or an equivalent portion may be readily accomplished by a cam member, ram or the like.

I claim:

1. In a tool for stripping cable sheaths, the combination of a first pair of jaws pivotally connected together and having inwardly directed faces provided with cutting edges, a second pair of jaws pivotally connected together and having inwardly directed faces for cable gripping, a rod connected to one of the pairs of jaws for displacing the same relative to the other pair of jaws, an actuating lever, and a three-link toggle having one of its links connected to said lever, a second of its links connected to said rod, and a third of its links connected to one pair of jaws which is not connected to said rod, all three links of said toggle being pivoted together at a common point.

2. The device as defined in claim 1 together with resilient means biasing said first and second pairs of jaws against relative displacement.

3. The device as defined in claim 1 wherein said lever is pivotally connected to one of the jaws in the second pair, said rod being connected to the jaws in the first pair.

4. The device as defined in claim 1 together with means provided on one jaw in one pair for adjusting the position of one jaw in the other pair relative thereto.

References Cited UNITED STATES PATENTS 1,151,319 8/1915 Wood 81-9.5 3,146,645 9/1964 Hindenburg et al 819.5

FOREIGN PATENTS 619,302 9/ 1935 Germany. 890,075 9/ 1953 Germany. 1,059,064 6/ 1959 Germany. 1,102,842 3/1961 Germany.

MILTON S. MEHR, Primary Examiner.

US. Cl. X.R. 81--367 23%;? UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,422,708 Dated January 21 1969 Inventor(s) Zdzislaw Bieganski It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the heading, after the line "Filed Oct. 4,

1967, Ser. No. 672,753", insert -Claims priority, application Great Britain,

June 3, 1967, 25,727/67-- Ihis certificate supersedes Certificate of Correction issued April 28, 1970.

SIGNED RND SEALED JUL 281970 (SEAL) Attest:

Edward M. Fletcher, Ir. WILLIAM w YI-m. JR- Attesfing Officer G'omissioner of Patents 

